I am wondering what happens if one runs svnadmin pack on a
repository at the same time as a client is performing a
checkout (for example). Is this supported, or is the
onus on the administrator to prevent access to the repository
while it is packed? I didn't see this mentioned in the release
notes or in the book.

I realize that this may be more of a usage question, but the
motivation is to try to specify the requirements for performing
an absolute obliteration on a live repository. If packing
requires repository access to be shut down, I don't think an
absolute obliteration operation should aim for more, agreed?

If svnadmin pack handles live repositories gracefully I would
be interested in determining whether the same method could be used
for obliteration, since it requires a complete rewrite of the
repository in the same way. If not, I would want the specification
to reflect that, since I would like the specification to be
reasonably implementable.